Eguchi Y, Ogawa T, Ogawa H
Department of Biology, Faculty of Science, Osaka University, Japan.
J Mol Biol. 1988 Nov 5;204(1):69-77. doi: 10.1016/0022-2836(88)90600-6.
The presence of either deoxyguanylyl-(3'----5')-deoxyguanosine (d(G-G] or deoxyadenylyl-(3'----5')-deoxyguanosine (d(A-G] greatly stimulates cleavage of the phage phi 80 cI repressor mediated by the Escherichia coli RecA protein in vitro. No other deoxydinucleoside monophosphate or riboguanylyl-(3'----5')-guanosine (r(G-G] affects the cleavage reaction. Neither the cleavage site of the phi 80 cI repressor nor the requirement for single-stranded DNA and ATP for cleavage is altered by d(G-G). Photoaffinity labeling experiments with 32P-labeled 5'-phosphoryl deoxyguanylyl deoxyguanosine (pd(G-G], which also stimulates cleavage, show that pd(G-G) bound to the repressor under the conditions in which the repressor is cleaved by RecA protein. The binding increases the affinity of the repressor for RecA protein and thus greatly stimulates repressor cleavage. The cleavage reactions of LexA and lambda cI repressors by RecA protein are not affected by d(G-G).
脱氧鸟苷酰 -（3'→5'）-脱氧鸟苷（d（G-G））或脱氧腺苷酰 -（3'→5'）-脱氧鸟苷（d（A-G））的存在极大地刺激了由大肠杆菌RecA蛋白在体外介导的噬菌体φ80 cI阻遏物的切割。没有其他脱氧单磷酸核苷或核糖鸟苷酰 -（3'→5'）-鸟苷（r（G-G））影响切割反应。d（G-G）不会改变φ80 cI阻遏物的切割位点，也不会改变切割对单链DNA和ATP的需求。用32P标记的5'-磷酸脱氧鸟苷酰脱氧鸟苷（pd（G-G））进行的光亲和标记实验也表明，pd（G-G）在阻遏物被RecA蛋白切割的条件下与阻遏物结合。这种结合增加了阻遏物对RecA蛋白的亲和力，从而极大地刺激了阻遏物的切割。LexA和λcI阻遏物被RecA蛋白的切割反应不受d（G-G）的影响。
